The planned May launch of NASA’s MESSENGER
spacecraft – the first designed to orbit the planet Mercury
­– has been rescheduled for no earlier than July 30.

The new launch period, a backup to the May
plan, extends from July 30-August 13, 2004. Several factors led
to NASA’s decision to move the launch from its original date,
including a desire to perform more testing of MESSENGER’s
fault-protection system software. This allows the spacecraft to
check its own health and, when necessary, switch between alternative
backup systems. This will also create some additional time for the
test team to complete final assembly and checkout, affording a more
comfortable spacecraft processing schedule.

MESSENGER will launch aboard a Boeing Delta
II rocket from Cape Canaveral Air Force Station, Fla. Under a new
mission profile, the spacecraft will return to Earth for a gravity
assist a year after liftoff; swing past Venus twice, then fly by
Mercury three times before starting a yearlong orbit of the innermost
planet in March 2011. MESSENGER’s science plans – to
provide the first images of the entire planet and collect detailed
information on the composition and structure of Mercury’s
crust, its geologic history, the nature of its thin atmosphere and
active magnetosphere, and the makeup of its core and polar materials
– remain intact.

MESSENGER recently completed a successful
three-month series of space-environment tests at NASA’s Goddard
Space Flight Center, Md., demonstrating that it could withstand
the rigors of launch and the wide range of hot and cold temperatures
it will face on its journey to and orbit around Mercury. On March
10, the spacecraft arrived in Florida, where technicians and engineers
have been processing it for launch at the Astrotech Space Operations
facility outside Kennedy Space Center. The spacecraft will continue
its processing activities at Astrotech, and the team is developing
a new schedule for the work leading up to the summer launch opportunity.

Visit the Mission
Design section for a look at MESSENGER's new path to Mercury.